Loop takers for lock stitch sewing machines



Sept. 16,1958 'E. P. SPAINE 2,351,977

LOOP TAKERS FOR LOCK STITCH SEWING MACHINES Filed Dec. 31, 1956 III/lb.A

IN VEN TORS Edwdrd F. Spaine WITNESS A TTORNE Y United States PatentLOOP TAKERS FOR LOCK STITCH SEWING MACHINES Edward P. Spaine,Bridgeport, Conn., assignor to The Singer Manufacturing Company,Elizabeth, N. J., a corporation of New Jersey Application December 31,1956, Serial No. 631,655 13 Claims. (Cl. 112-231) This invention relatesto sewing machines of the lock stitch type and more particularly to aloop taker assembly provided with a thread mass enclosing means adaptedto carry a supply of locking thread with which the needle thread isconcatenated to form a lock stitch.

The present invention has for its primary object to provide a loop takerassembly having a thread mass enclosing means or thread case which isconstructed and arranged to carry the supply of locking thread in theform of a prewound cop from which the thread unwinds from its center.

As is well known, the use of a center unwind cop has many advantagesover the bobbin type of thread source, particularly in that the threadcop affords a greater thread capacity and also eliminates the usual timeconsuming thread winding operation that is required when theconvention-al bobbin is used. Heretofore, in the adaptation of looptaker assemblies to receive center unwind cops, difficulties have beenencountered in controlling the passage of the thread from its threadcase. These difliculties are particularly evident during the high speedoperation required of present day sewing machines wherein it is foundthat the thread mass unwinds in coils which at times emerge from thethread-case causing the thread to twist and thereby form kinks makingthe usual critical locking thread requirements for proper stitchformation difiicult to achieve. This action of the thread cop is causedby the inherent characteristics imparted to the cop during themanufacture thereof.

A thread cop is generally prepared by cross winding the thread and undersome circumstances compressing the wound thread mass thereby to maintainthe cop substantially rigid to withstand the required handling thereofand to eliminate growing of the cop due to the effects of humidity. Thepreparation of a thread cop in this manner tends to create temporarykinks in the thread whereby when a length of the thread is unwound fromthe cop within the thread case of the loop-taker the unwound threadtends to return to the kinked form. It is this kinking condition whichcauses difiiculties in maintaining the proper thread control of thelocking thread.

It is accordingly a further object of the present invention to provide athread case with a thread controlling device which will control thepassage of thread from the thread-case in a manner to smooth and ironthe thread to remove any twists or kinks which may be present.

It is another object to provide a novel thread case assembly which isconstructed in a manner such that the replenishing of the supply oflocking thread may be facilitated.

It is a further object to provide a novel loop-taker assemblyincorporating a thread case which is adapted to receive a locking threadsource in the form of a thread cop which unwinds from its center.

With the above and other objects in View, as will here inafter appear,the invention comprises the devices, combinations and arrangement ofparts hereinafter set forth and illustrated in the accompanying drawingsof a preferred embodiment of the invention, from which the severalfeatures of the invention and advantages attained thereby, will bereadily understood by those skilled in the art.

In the accompanying drawings:

Fig. 1 is a fragmentary front elevational view of a sewing machineequipped with a horizontal axis loop taker embodying the invention.

Fig. 2 represents a horizontal sectional view taken substantially alongthe line 2-2 of Fig. 1 with the loop seizing member of the loop takerrotated approximately from the position shown in Fig. 1.

Fig. 3 represents a vertical sectional view of the looptaker and itsthread-case.

Fig. 4 is an exploded view of the loop taker assembly embodying thepresent invention showing a fragmentary portion of the loop seizingmember.

Referring to the drawings, the present invention has been embodied in alock-stitch sewing machine having a throat plate 10 formed with a needlehole 11 and supported in a bed 12. Disposed below the throat plate 10 isan oscillating shuttle loop taker assembly 13 which is carried in theusual manner in a bed supported housing 14 of the type disclosed in theE. B' Allen Patent No. 1,869,402, August 2, 1942.

The loop taker assembly 13 comprises a loop seizing member 15 in theform of a substantially semicircular discoi-dal casing having asubstantially closed rear end wall 16 and a forward open end defining anaxial hollow 17. The loop seizing member 15 is provided adjacent theopen end with the usual loop seizing beak 18 and with a peripheralbearing rib 19 which seats within the raceway 20 formed in the housing14, wherein the loop seizing member 15 is oscillated in the usual mannerby the loop taker actuating shaft 21 having an actuating dog member (notshown) which is adapted alternately to engage the impact faces 15aformed on the ends of the bearing rib 19.

Disposed within the axial hollow 17 of the loop seizing member 15 is atwo part thread casing assembly 22 including a thread case holder 23 anda thread case 24. The holder 23 is cup shaped having a circular flange25 projecting laterally from the periphery of a disc 26 forming thebottom wall of the holder 23. The outer surface of the bottom wall 26 isformed with a raised axially disposed boss 27 and a hub 28 whichrotatably seats within an axial opening 29 provided in the rear end wall16 of the loop seizing member 15. A stud 30 threaded into the rear endwall 16 and swagged on its inner end maintains the holder 23 on the loopseizing member 15. To permit free and non-binding relative oscillationof the shuttle 15 and the holder 23 the stud 30 is formed with a taperedhead 31 which is prevented from making direct contact with the rearshuttle wall 16 by a domeshaped spacing member 32 which seats within acircular recess 33 formed on the outer surface of the wall 16.

The outer surface of the circular flange 25 is formed with a peripheralrecess 34 in which there is seated a latching detent in the form of aleaf spring 35, one end of which is fixedly secured to the flange 25 bya rivet 36 and the other end having a semi-spherical protuberance 37which is adapted to project through an opening 38 formed in the flange25 and into the interior of the holder 23, whereby the semi-sphericalprotuberance 37 may engage the thread case 24 to maintain it latchedwithin the holder 23 as will later be described.

The thread case 24 is also cup shaped having a substantially flat topwall 39 and an integral cylindrical wall 40 having an open end defininga thread cop receiving opening. The cylindrical wall 40 is sizedslidably to interfit within the cylindrical flange 25 of the holder 23and forming therewith an enclosed thread housing 41. For the purpose ofmaintaining the thread case 24 latched to the holder the lower end ofthecylindrical wall 40 is provided with an annular groove 42 which islocated such that when the rim of the cylindrical wall 40 is inengagement with the holder bottom wall 26 the semi-sphericalprotuberance 37 on the leaf spring 35 will resiliently seat therein.

Attached to the top wall 39 and disposed along a chord line spaced fromthe center thereof is an outwardly projecting semi-circular thread casefinger piece 43 having an upwardly extending portion which projectsheyondthe cylindrical wall 40 and is slightly bent at an angle to thechord line to form a thread case rotation restraining finger 44 which isadapted to be disposed within the usual thread case rotation restrainingnotch 45'provided in the shuttle housing 14. To facilitate the handlingof the thread case 24 during the insertion and removal thereof from theholder 23 the finger piece may be provided with a thumb and forefingerengaging slot 46. It will be appreciated that the semi-circular contourof the finger piece 43 provides a smooth uninterrupted surface overwhich the usual needle thread loop, formed during the loop seizureportion of the stitching cycle, may be shed.

Centrally located on the top wall 39 of the thread case 24 is a threaddelivery eye 47 through which the thread emerges during sewing.Communicating with the thread delivery eye 47 to thread the case 24 is athreading slot 48 which extends radially from the eye 47 along the topwall 39and down the cylindrical wall 40 opening at the rim thereof.

'Parallel to the thread case finger piece 43 there is formed adiametrical'recess 49 opening at one end into the cylindrical wall 40.The recess 49 has a substantially flat bottom surface 50 along its majorlength and slightly beveled surface 51 adjacent to the cylindrical wall40. Disposed within the recess 49 there is a thread controlling meanswhich serves to restrict the passage of the thread emerging from thethread casing and which also serves to straighten and tension thethread. To this end, there is provided in the recess 40 a substantialflat rectangular ironing plate 53 having secured adjacent one endthereof a projecting stud 54 which enters the thread delivery eye 47 anddefines an annular opening 55 through which only a single thickness ofthread may emerge. The ironing plate 53 is disposed flush on the bottomsurface 50 of the recess 49 with one edge spaced from the edge of therecess intersecting the threading slot 48 thereby forming a threadgroove 56 permitting the insertion of the thread beneath the ironingplate 53 and into the annular opening 55. To further facilitatethreading of the casing the corner of the ironing plate overlying thethreading slot may be rounded as shown and the other end portion of theplate lying over the beveled surface 51 of the recess may be formed withthe nose 57 which is angularly bent downwardly and spaced above thebeveled surface 51 to provide a thread entrapment space. As shown, whenthe thread case 24 is threaded the thread t passes from the annularopening into a tapering V-notch 58 formed in the bottom surface 51 ofthe recess 40 and thence between the fiat ironing plate 53 and the flatsurface 50 f the recess wherein the kinks and twists which may bepresent are removed to provide a straightened thread which isconcatenated with the needle thread to form a lock stitch in the usualmanner.

To maintain the ironing plate 53 on the top wall 39 under the desiredironing pressure and to provide a tension on the locking thread 1 thereis overlying the ironing plate 53 a tension leaf spring 59. One end ofthe tension leaf spring 59 extends below the stud end of the ironingplate 53 and the thread delivery eye 47 and is secured to the top wallby a screw 60 which is adjustable to vary the tension of the leafspring. The other end of the leaf spring 59 overlying the ironing plateis formed with a slot 61 receiving a fastening screw 62 which alsopositions the ironing plate on the top wall.

As shown, the screw 62, securing the ironing plate 53 and the overlyingupper end of the leaf spring 59 to the top wall 39, also serves as aguide post for maintaining the thread I beneath the ironing plate as ittravels upwardly toward the cylindrical wall 40. Mounted on thecylindrical wall 44) by screws 63a or the like is a bowed thread guide63 having formed adjacent one end thereof an inclined thread guidingnotch 64 which is angularly displaced from the thread guiding screw 62in the direction of the thead case finger piece 43 and lies adjacent anelongated needle clearance opening 65 formed in the cylindrical wall 40.

The present shuttle assembly is particularly adapted for use with athread cop C adapted snugly to fit within the thread receiving cavity 41defined by the thread case 24 and holder 23 and having a strand ofthread t so wound that it may be drawn from the center. Prior toinserting the thread cop C in the thread case 24 a length of thethread 1. is drawn from the center of the cop C and inserted through thethreading slot 48 and along the threading space 56 adjacent the sidewall of the recess 49 and beneath the nose 57 of the ironing plate 53,whereupon it is tautly drawn sidewise beneath the plate 53 until thethread abuts against the guiding post screw 62 and the thread passesbeneath the rounded corner of the ironing plate 53 into the annularopening 55 and is seated in the tapering V-notch 58. Thereafter thethread is laterally inserted into the thread guiding notch 64 of thethread guide 63. After the thread case 24 is threaded it is insertedinto the holder 23 with the rim of the cylindrical wall 40 in engagementwith the bottom wall, whereupon the semi-spherical protuberance 37 onthe leaf spring 37 carried by the holder 23 snaps into the groove 42 ofthe cylindrical wall 40 to retain the thread case latched to the holder.The shuttle 15 carrying the threaded thread case assembly 22 is thenready to provide a locking thread for the formation of a lock stitch inthe usual manner.

The structure of the present invention has many advantages particularlywith respect to the means for controlling passage of thread t from thethread casing 22. As previously mentioned, thread cops have a tendencyto unwind in coils with the thread thereof having a temporary setresulting in kinks and if these are not controlled the thread becomessnarled. By the present invention while the coils may still form theyare maintained within the thread casing 22 since the annular opening 55provides a minimum space through which only a single strand of threadmay pass, thereby retaining the coils within the casing. By passing thethread through the restricted opening 55 and then between the tensionedironing plate 53, the flat surface 50 of the top wall 40, any kinks ortwists which may have been present in the thread due to its coilingcharacteristics are removed.

Having thus set forth the nature of the invention, what I claim hereinis:

1. A thread case for sewing machine loop takers comprising a cop cavitydefining cup-shaped body having a cylindrical side wall and including asubstantially fiat top wall, a thread delivery eye formed in said topwall through which thread can be delivered from the center of a cop insaid cop cavity, and thread controlling means mounted on said top walland overlying said thread delivery eye, said thread controlling meansincluding means disposed to enter said thread delivery eye to form arestricted opening for preventing the passage of kinks of the cop threadthrough said thread delivery eye, and means adjacent said threaddelivery eye cooperating with said substantially flat top wall forengaging a cop thread emerging from said thread delivery' eye betweensaid means and said top wall for ironing and tensioning the thread.

2. A thread case for sewing machine loop takers comprising a cop cavitydefining cup-shaped body having a cylindrical side wall and including asubstantially flat top wall, a thread delivery eye formed in said topwall through which thread can be delivered from the center of a cop insaid cop cavity, and thread controlling means mounted on said top walland overlying said thread delivery eye, said thread controlling meansincluding a thread restricting stud disposed toenter said threaddelivery eye to form an annular opening for preventing the passage ofkinks of the cop thread through said thread delivery eye, and meansadjacent said thread delivery eye cooperating with said substantiallyflat top wall for engaging a cop thread between said ironing means andsaid top wall for ironing and tensioning the thread.

3. A thread case for sewing machine loop takers comprising a cop cavitydefining cup-shaped body having a cylindrical side wall and including asubstantially flat top wall, a thread delivery eye formed in said topwall through which thread can be delivered from the center of a cop insaid cop cavity, a plate lying flush on said top wall and overlying saidthread delivery eye arranged to cooperate with said top wall to iron athread after it emerges from said eye, a stud carried by said plateentering said thread delivery eye forming an annular opening forpreventing the passage of kinks of the cop thread therethrough, andadjustable spring means overlying said plate imparting an ironingpressure thereon and simultaneously providing a tension on the thread.

4. A thread case for sewing machine loop takers comprising a cop cavitydefining cup-shaped body having a cylindrical side wall and including asubstantially flat top wall, a thread delivery eye formed in said topwall through which thread can be delivered from the center of a cop insaid cop cavity, a plate lying flush on said top wall overlying saidthread delivery eye and arranged to cooperate with said top wall to ironsaid thread after it emerges from said eye, a stud carried by said plateentering said thread delivery eye forming an annular opening forpreventing the passage of twisted or kinked cop thread therethrough,adjustable spring means overlying said plate, imparting an ironingpressure thereon and simultaneously providing a tension on the thread,and means for attaching said plate and said spring means on said topwall, said attaching means arranged to guide the thread beneath saidplate after emerging from said annular opening.

5. A thread case for sewing machine loop takers comprising a cop cavitydefining cup-shaped body having a cylindrical side wall and including asubstantially flat top wall, a thread delivery eye formed in said topwall in substantial alignment with the center of said cavity, adiametrical recess formed in said top wall and having a substantiallyflat bottom surface, a radial threading slot formed in said casing withthe inner end opening into said thread delivery eye and said outer endopening into the rim of said cylindrical side wall, a plate overlyingthe thread delivery eye lying flush on said flat bottom surface of saidrecess, a stud carried by said plate and entering said delivery eyeforming an annular opening through which only a single strand of threadmay emerge, a leaf spring having an upper end and a lower end, said leafspring upper end overlying said plate and said lower end projectingbeyond said plate into said recess, an adjustment screw securing saidlower end of said leaf spring to said top wall, and a fastening memberpositioning said plate and said overlying upper end of the leaf springin said recess, said fastening means being arranged to provide a guidingpost for maintaining the travel of the thread beneath said plate afterthe thread emerges from said annular opening.

6. A shuttle for a lock stitch sewing machine comprising a discoidalloop seizing member formed with an axially disposed cavity, a threadcase holder having a bottom wall, a stud axially positioned on said loopseizing member and journaling said thread case holder within said cavityto permit relative circular movement between said loop seizing memberand said holder, a cup-shaped thread case having a cop receiving openingand a cylindrical side wall and having a top wall opposed to said threadcase holder bottom wall to define with said bottom wall an enclosed copreceiving housing, and means operatively associated with saidcylindrical side wall and thread case holder releasably latching saidthread case to said thread case holder.

7. A shuttle for a lock stitch sewing machine comprising a discoidalloop seizing member formed with an axially disposed hollow, a threadcase holder having a bottom wall and a cylindrical flange, a studaxially positioned on said loop seizing member journaling said holderwithin said hollow, a cup-shaped thread case having a cop receivingopening and a cylindrical side wall interfitting said thread case holdercylindrical flange and having a top wall opposed to said bottom wall ofsaid thread case holder to define with said bottom wall an enclosed copreceiving cavity, and a detent operatively associated with saidcylindrical wall and said thread case holder flange releasably latchingsaid thread case to said thread case holder.

8. A shuttle for a lock stitch sewing machine comprising a discoidalloop seizing member formed with an axially disposed hollow, a threadcase holder having a bottom wall and a cylindrical flange, a studaxially positioned on said loop seizing member journaling said threadcase holder within said hollow to permit relative circular movementbetween said loop seizing member and said thread case holder, acup-shaped thread case having a cop receiving opening and a cylindricalside wall interfitting said holder cylindrical flange and having a topwall opposed to said bottom wall of said thread case holder to definewith said bottom wall an enclosed cop receiving cavity, and resilientmeans mounted on said thread case holder flange engaging saidinterfitting cylindrical wall to releasably latch said thread case tosaid thread case holder.

9. A shuttle for a lock stitch sewing machine comprising a discoidalloop seizing member formed with an axially disposed hollow, a threadcase holder having a bottom wall and a cylindrical flange, a studaxially positioned on said loop seizing member journaling said threadcase holder within said hollow to permit relative circular movementbetween said loop seizing member and said holder, a cup-shaped threadcase having a cop receiving opening and a cylindrical side wallinterfitting said cylindrical flange of said thread case holder, aperipheral groove formed in the portion of the cylindrical wall fittingwithin said flange, and a spring detent mounted on said flange andadapted to seat within said groove of said cylindrical wall toreleasably latch said thread case to said thread case holder.

10. A thread case assembly for sewing machine loop takers comprising athread case holder having a bottom wall and a cylindrical flange, acup-shaped thread case having a cop receiving opening and a cylindricalside wall interfitting said flange of said thread case holder, aperipheral groove formed in the portion of the cylindrical wall fittingwithin said flange, and a spring detent mounted on said flange adaptedto seat within said groove of said cylindrical wall to releasably latchsaid thread case to said thread case holder.

11. A thread case assembly for sewing machine loop takers comprising athread case holder having a bottom wall and a cylindrical flange, acup-shaped thread case having a cop receiving opening and a cylindricalwall interfitting said flange of said thread case holder, meansoperatively associated with said flange and said cylindrical wallreleasably latching said case to said holder, and

I an outwardly projecting finger piece mounted on said top Wall endhaving a portion thereof extending beyond said cylindrical wallproviding a thread case rotation restraining finger adapted to seatwithin a rotation restraining notch of a loop taker housing, said fingerpiece being of a substantially semi-circular contour to provide a needleloop shedding surface.

12. A thread case assembly for a sewing machine loop taker comprising acop cavity defining a cup-shaped body having a cylindrical side wall andincluding a substantially flat top wall, a thread delivery eye formed insaid top wall through which thread can be delivered from the center of acop in said cop cavity, a plate lying flush on said top wall overlyingsaid thread delivery eye and arranged to cooperate with said top wall toiron said thread after it emerges through said eye, a stud carried bysaid plate entering said thread delivery eye forming an annular openingpreventing the passage of twisted or kinked cop thread therethrough, anadjustable spring 8 means overlying said plate imparting an ironingpressure thereon and providing a tension on the thread, an outwardlyprojecting finger piece mounted on said top wall and having a portionthereof extending beyond said cylindrical wall providing a thread caserotation finger adapted to seat within a rotation restraining notch of ashuttle housing.

13. The invention as defined in claim 12 in which the finger piece isarcuately contoured to provide a needle loop shedding surface.

References Cited in the file of this patent UNITED STATES PATENTS467,461 Benson Jan. 19, 1892 1,981,834 Fleckenstein Dec. 29, 19322,420,695 Best May 20, 1947 2,664,059 Eriksson Dec. 29, 1953

